1. Field of the Invention
The present invention relates to a transmitting system utilized in a small-sized vehicle such as a motorcycle, a four-wheel buggy and the like, and particularly, to an improvement in a transmitting system utilized in a small-sized vehicle, in which a crankshaft of an engine and an input shaft of a multi-stage transmission, which is disposed in parallel to the crankshaft, are leading to each other through a fluid transmitting means including a pump impeller leading to the engine, and a turbine impeller connected to the multi-stage transmission.
2. Description of the Related Art
There are such already known transmitting systems for small-sized vehicles, in which the fluid transmitting means is comprised of a torque converter, as disclosed in, for example, Japanese Patent Application Laid-open No. 57-69163.
In such known transmitting system, as described in the above Publication, the crankshaft of the engine and the input shaft of the multi-stage transmission are connected to each other only through the torque converter, so that a torque shock generated at the time of the starting the vehicle or during shifting is absorbed by a slipping action of the torque converter.
However, the known transmitting system suffers from the following drawbacks: The torque converter or the fluid coupling has a slipping function, but performs the transmission of a torque to certain degree, as long as a power is input from the engine to the torque converter or the fluid coupling. Therefore, in the known system, at the time of starting the vehicle in which the transmission is switched over from a neutral position to a low or first-speed position, a creep phenomenon is produced in which power is transmitted to a driving wheel of the vehicle to certain degree, even if the engine is in an idling state. During traveling of the vehicle, the friction always occurs in switching and sliding portions of the transmission due to the transmitted torque. For this reason, there are inconveniences that the resistance to the switching of the transmission is large, and a large shifting load is required. In addition, the torque converter is mounted to the input shaft of the multi-stage transmission driven in a decelerated manner from the engine and for this reason, the transmitted torque borne by the torque converter is relatively large, and hence, a large-sized torque converter having a large capacity is obliged to be used. This makes it difficult to provide the compactness of the power unit including the engine and the transmission.